Solid-state imager and solid-state imaging device

Abstract

There is provided a single-chip color solid-state imager of a backside illumination type having high sensitivity and low noise that facilitates the miniaturization of a pixel size. A pixel readout circuit is selectively disposed on a part of pixels of a readout block consisting of a plurality of pixels that share the pixel readout circuit.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2007-4429 filed on Jan. 12, 2007 in Japan, the entire contents of which are incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a solid-state imager and a solid-state imaging device.[0004]2. Related Art[0005]Due to the diffusion of digital cameras, camera-mounted mobile phones and the like in recent years, demands for solid-state imagers have been increased. In particular, demands for CMOS solid-state imagers that can be manufactured using a CMOS process, which is an ordinary semiconductor manufacturing process, have been increased. In recent years, further down sizing and larger numbers of pixels mounting have been required to such solid-state imagers, and the miniaturization of pixel sizes causes an important problem.[0006]That is, compared with the redu...

AI Technical Summary

Benefits of technology

The present invention provides a color solid-state imager with high sensitivity and low noise. The pixel size can be easily minimized. The imager includes a semiconductor substrate with pixels arranged in a matrix form, a transfer transistor, and pixel readout circuits. A readout portion reads electrical signals from the pixels, and a color filter array is provided on the backside of the substrate. The invention also includes an optical lens system and a signal processing portion to process the electrical signals outputted from the imager.

Problems solved by technology

In recent years, further down sizing and larger numbers of pixels mounting have been required to such solid-state imagers, and the miniaturization of pixel sizes causes an important problem.

That is, compared with the reduction of plane size parallel to the surface of a semiconductor substrate accompanying the miniaturization of pixels, the reduction in the depth direction vertical to the surface of a semiconductor substrate has not been scaled at the same time, and problems caused thereby have been actualized.

Specifically, since the distance between the surface of the silicon substrate on which a photodiode is formed and the micro lens for optically expanding the aperture ratio is not reduced even if the size of the pixel region in the horizontal direction is reduced, a phenomenon known as “eclipse” or “vignetting” wherein a part of incident light is reflected by a metal wiring layer in the peripheral portion of the pixel region where incident light from the imaging lens diagonally enters occurs in the peripheral portion of the pixel region, and the non-uniformity of sensitivity is caused.

However, when long-wavelength light wherein the absorption coefficient of the silicon substrate is low, and the penetration length of incident light is large was imaged, there was a problem wherein the incident light passes through the rear surface side photodiode, reaches the surface side readout circuit region, and the operation of the readout circuit is modulated by electron-hole pairs generated there.

Consequently, the photodiode formed on the rear surface side could not be designed to be sufficiently large, and the effect of improving the aperture ratio of the photodiode by back-face was insufficient.

Specifically, the effect to improve the aperture ratio of the backside photodiode, or the effect to expand the area of the surface side readout circuit is not fully obtained.

Images